The present invention relates to a punch or punching apparatus for punching documents when such documents or the like are to be filed.
A punching apparatus is disclosed as a conventional art in Japanese Patent Laid-Open Publication No. Hei 6-55499. In the punching apparatus disclosed in this publication, a punch portion is fitted in a punch-portion moving groove formed in a casing, and the moving punch portion is formed along the punch-portion moving groove. Then, the punch portion is fixed to an endless belt laid between a driving gear and a driven gear and is moved by the rotation of the driving gear rotated by a motor.
Also, in the drive mechanism of the punching apparatus installed in the punching portion, a crankshaft having a tip end at which a punch is connected by a pin is supported at its intermediate portion to be swingable, an oblong hole is formed in a rear end of the crankshaft connected to a crank, a gear is engaged with the crank, the gear is rotated by the motor (assuming that the motor is installed on the punch portion), the crankshaft is swung to thereby move the punch up and down, the punch is in coupling engagement with coupling hole formed on the casing side, and the punching in effected by a shearing force between the punch and the coupling hole.
A punch position setting guide formed in advance in conformity with the number and the pitch of holes is selected. The punch position setting guide is set under a guide detecting sensor provided in the punch portion to detect it. The motor for driving the gear to swing the above-described crankshaft and the motor of the driving gear for driving the above-described belt are controlled to thereby form the predetermined number of holes at a predetermined interval of the pitch.
In the above-described punching apparatus, since the punch portion is moved under the status where it is inserted into the punch-portion moving groove formed in the casing, when the holes are to be formed in the paper by the punch, there generates not a serious problem in the case where the number of pieces of paper is small. However, in the case where the number of pieces of paper is large, it is necessary to apply a relatively large force to the paper when punching them. Since this force is received by the punch portion, when punching the holes, the firm fixation is necessary to the punch portion to endure the force. Then, since the coupling hole is formed on the casing side, the pressing force of the punch may act on the punch portion as a reaction force. If the punch portion loses the fixing force, the punch could not be inserted into the coupling hole. As a result, it is practically impossible to insert the punch into the coupling hole. Further, undesirable friction is generated between the punch and the coupling hole, resulting in the reduction in cutting effect of the punch to shorten a life of the punch. Accordingly, only by the insertion of the punch portion into the punch-portion moving groove, there is no function to firmly fix the punch portion against the above-described reaction force. In order to firmly fix the punch portion, its structure is complicated and high-priced.
Also, since the punch is provided at the tip end of the swingable crankshaft, the force for pressing down the punch is not in the vertical direction. For this reason, in the case where a considerably large force is applied to the punch downwardly, an axis of the punch is displaced due to the relationship with the punching resistance, so that the undesirable friction is generated between the punch and the coupling hole. In the same manner as described above, the cutting effect of the punch is degraded to shorten a life of the punch.
Also, since the motor as the drive source for the crankshaft is mounted on the punch portion, a weight of the punch portion is increased, and the inertia when the punch portion is moved or stopped is increased. In particular, when the punch portion is driven by the belt, it is difficult to stop the moving punch portion having a large inertia in a suitable position. Also, since the inertia is large, it is impossible to move the punch portion at a high speed, resulting in poor efficiency of punching. Also, in the case where the motor is mounted on the moving punch portion, since the electric wirings are necessary between the motor and the power source which is located in the stationary portion, the wirings are dragged whenever the punch portion is moved. Therefore, there is a high possibility of damages such as a cut of the wirings and the like.
In order to solve the above-noted defects, the present applicant has proposed a punching apparatus in Japanese Patent Laid-open Publication No. Hei 8-206996. Its concept will now be described with reference to FIGS. 9 and 10. In FIG. 9, a slide transmission shaft 2 and a screw rod 3 are provided in parallel through a head 1. Also, a rectangular pillar is used as the slide transmission shaft 2. Reference numeral 4 denotes a rail for guiding the head 1 when it moves in directions indicated by arrows b. Four guide wheels 5 are engaged with the rail 4 so as to clamp the rail 4 in the vertical direction. Then, the four guide wheels 5 are rotatably supported to a support member 6 mounted on the head 1.
The head 1 is composed of a side wall 7 and a side wall 8. A guide member 9 is provided on a side surface of the side plate 7 so that the punch of a punch portion 10 provided under the guide member 9 is moved up and down along the guide member 9. Also, a punch-hole positioning portion 11 for determining the position of the punch while adjusting an insertion amount of the paper P is provided rotatably as indicated by arrows. The punch-hole positioning portion 11 is positioned by a punch-hole positioning regulator 12. Reference numeral 14 denotes an operation section in which gears for rotating the slide transmission shaft 2 and the screw rod 3 and the like are installed. Reference numeral 15 denotes a knob for operating a dog 16 for selecting the number of the holes and the pitch of the holes. Reference numeral 17 denotes limit switches for stopping the movement of the head 1, which are provided on both sides of the head 1 (not shown) and are provided movably to a support rod 18 so as to limit the movement range of the head 1 in response to a kind of paper P.
Namely, for example, when the head 1 is moved in the right direction while punching to complete the punching up to a predetermined position at the right end of the paper P, the head 1 is brought into contact with the limit switch 17 on the right side and stopped. Next, when the new paper P is set and the switch is turned on, the head 1 is moved in the opposite direction, i.e., on the left side while punching to complete the punching up to a predetermined position at the left final end of the paper P, the head 1 is brought into contact with the limit switch 17 on the left side and stopped. Thus, the punching is effected while the head 1 is being reciprocated so that the punching efficiency is enhanced and it is possible to set the punching positions of the final ends on the right and left sides by moving the limit switches 17 in relation with the size of the paper and the pitch between the holes.
As shown in FIG. 10, in the interior of the operating portion 14, a cam 19 is fixed to an end portion of the slide transmission shaft 2, and it is rotated by a motor (not shown) together with the cam 19. The limit switch 20 is turned on and off by the cam surface 191 of the cam 19, so that the slide transmission shaft 2 is rotated and stopped. Namely, a recessed cam surface 192 with which a movable piece 201 of the limit switch 20 does not slidingly contact is formed on the cam surface 191 of the cam 19. When the limit switch mounted on the head 1 is located at the recess portion of the dog 16 and is in the state "on", the motor for rotating the slide transmission shaft 2 is driven, and the movable piece 201 of the limit switch 20 is brought into sliding contact with the cam surface 191 to keep the rotation of the motor. When the slide transmission shaft 2 is rotated through one turn, the movable piece 201 of the limit switch 20 is located at the cam surface 192. The rotation of the motor is stopped, the rotation of the slide transmission shaft 2 is stopped.
Also, a driven gear 21 is fixed to an end portion of the screw rod 3. The screw rod 3 is rotated by the driving gear 22 fixed to the shaft of the motor. Namely, the movable piece of the limit switch mounted on the head 1 is brought into sliding contact with the recessed portion of the dog 16 so that the limit switch is turned on to rotate the motor for rotating the slide transmission shaft 2. The slide transmission shaft 2 is rotated through one turn so that the movable piece 201 of the limit switch 20 is located on the cam surface 192 to turn off the limit switch 20. As a result, the motor for driving drive gear 22 is driven to move the head 1. Also, the motor may be rotated in the forward direction and the reverse direction. Also, in FIG. 10, when the slide transmission shaft 2 is rotated and a punching-pin driving gear 25 in rotated, a pin driven gear 24 engaged with the driving gear 25 is rotated. A driving member 23 mounted eccentrically on the pin driven gear 24 is engaged with an oblong hole 27 formed in a slider 26. The slider 26 is moved up and down. The punching pin 32 mounted on the slider 26 is moved up and down in the vertical direction.
In the punching apparatus shown in FIGS. 9 and 10, the movement of the head 1 in the directions indicated by arrows b (in the boring pitch directions) is carried out by the screw shaft, and the up-and-down movement of the punching pin is carried out by the slide transmission shaft. The timing between the both is taken by the cam and the limit switches. Accordingly, the structures become complicated. Also, since the intermittent movement of the head is carried out by the rotation and the rotation stop of the motor, in the high speed intermittent movement of the head, the inertia also works due to the weight of the head. There is a limit to the high speed intermittent movement of the head.